Content repositories, voting sites, and other social collaborative networks, such as public photograph, journal and video sites, typically contain a vast amount of content. One problem with such sites is that it can be difficult for users to locate desirable or interesting content among other, less interesting content. The problem can be exacerbated if such sites accept user-submitted content. Unscrupulous individuals may attempt to leverage the popularity of the site for financial gain, such as by directing traffic to advertising and other self-promotional material (e.g., spamming). Similarly, well-intentioned visitors may inadvertently clutter the portal, such as with duplicate content. In both cases, legitimate content is made all the more difficult to locate.